THE boss of the National Australia Bank has admitted its multi-million-dollar relationship with drugs boss Tony Mokbel was not acceptable.

Cameron Clyne said he would examine how the NAB loaned Mokbel millions of dollars to invest in property and expensive cars at a time his reported taxable income was $160 a week and when police were closing in on his drug empire.

This is not the sort of individual that, knowing what we know now, we'd want to bank.

Mr Clyne said he planned to dig out the bank's Mokbel files to find out what went wrong.

photo galleryThe many faces of Mokbel

Tony Mokbel leaving court in 2004.

1 of 6

Tony Mokbel outside court in 2005.

2 of 6

Tony Mokbel smiles leaving a Magistrates' court hearing in 2005.

3 of 6

Tony Mokbel leaves the Victorian Supreme Court in 2005.

4 of 6

A police handout released in 2007 shows Tony Mokbel, wearing a wig, after his arrest in the coastal Athens suburb of Glyfada. Picture: AFP

5 of 6

And Tony Mokbel in a mug shot without his wig. Picture: AFP

Read more on Tony Mokbel atheraldsun.com.au

6 of 6

Tony Mokbel leaving court in 2004.

Tony Mokbel outside court in 2005.

Tony Mokbel smiles leaving a Magistrates' court hearing in 2005.

Tony Mokbel leaves the Victorian Supreme Court in 2005.

A police handout released in 2007 shows Tony Mokbel, wearing a wig, after his arrest in the coastal Athens suburb of Glyfada. Picture: AFP

And Tony Mokbel in a mug shot without his wig. Picture: AFP

Read more on Tony Mokbel atheraldsun.com.au

1 of 6

"I'll be having a close look at it," he said. "I don't know the facts of where his money was coming from at the time. We don't condone any form of business practice that's illegal.

"If we knew what we know now, different decisions might have been made. It's not acceptable."

Mr Clyne said he believed the dealings with Mokbel were an "oversight".

"This is not the sort of individual that, knowing what we know now, we'd want to bank. It's not the sort of culture we want to bank," he said.

The court documents show it took just six years for the suburban pizza maker who was facing bankruptcy to build a property portfolio valued at more than $15 million.

Mokbel propertiesSource:Herald Sun

Properties previously owned by Tony Mokbel. Some were sold before authorities caught up with the drug kingpin and seized the rest. Picture: Herald Sun

Although the courts have seized and sold all his known assets, in 2005 police believed at least $9.4 million in Mokbel money was unaccounted for. Mokbel's tax returns show that while he was claiming a yearly income of $8310, he was driving a Ferrari and buying million-dollar properties.

Mr Clyne said the bank fully cooperated with police. He said he did not know if the NAB was still owed money by Mokbel.